Nickel base alloy having improved stress rupture properties



United States Patent 3 526 499 NICKEL BASE ALL OY HAVING IMPROVED STRESSRUPTURE PROPERTIES Richard J. Quigg, South Russell, and Henry E.Collins,

gi zf g ghgggb fz fi g to TRW Cleveland 5 about to hours. In contrast,the alloys of the present No Drawing. Filed Aug. 22, 1967, Ser. No.662,305 invention have a stress rupture life of at least hours Int. C1,C22(: 19/00 under the same conditions and consistently exceed 30 US. Cl.75171 10 Claims hours. The most preferred embodiments of the invention10 have an average stress rupture life under these conditions in excessof 60 hours.

ABSTRACT OF THE DISCLOSURE SUMMARY OF THE INVENTION This inventionrelates to nickel base superalloys par- A mFkel Superancy Partlcularb'for use 15 ticularly useful for jet engine parts including blades,vanes,- turbme englne blades because of P vastly F Y buckets, and thelike, the alloys consisting essentially of stress rupture properties andother physical characteristics, the following ingredients: the alloycontaining 0.05 to 0.25% carbon, from 5 to Percent 8% chromium, from 0.5to 4.0% molybdenum, from 0.5 Carbon 0.05025 to 2.0% titanium, from 4.5to 6.5% aluminum, from 1 20 Chromium to 10% cobalt, from 4 to 8%tungsten, from 0 to 2% Molybdenum rhenium, from 0.2 to 3.0% hafnium,from 0.01 to 0.50% Titanium zirconium, from 0.005 to 0.200% boron, from6 to 10% Aluminum tantalum, from 0 to 2% columbium, from 0 to 1% vana-Cobalt 140 dium, and the balance being essentially nickel, all per- 25Tungsten centages being by weight. Rhem-um Hafnium 0.2-3.0 Zirconium0.01-0.50 The invention described herein was made in the per- BoronO'OOLO'ZOO Tantalum 6-10 formance of work under a NASA contract and issub ect Columbium 0-2 to the provisions of Section 305 of the NationalAero- Vanadium nautics and Space Act of 1958, Public Law 85-568 (72Nickel Stat. 435; 42 U.S.C. 2457). 1E Pi g;

Rights to practice the invention for any use primarily ssen la y e arelated to aeronautical and space applications are availa- The Sum of emolybdenum, tungsten, and tantalum ble through the National Aeronauticsand Space Adminis- :Qntents Should be? 1114116 range 'P about 15 to 20%,nation with the tungsten being present in an amount greater than themolybdenum but less than the amount of tan- BACKGROUND OF THE INVENTION40 talllm- Within the broader ranges specified above, particularly Thepresent invention is in the field of nickel base improved alloys areprovided with the following superalloys particularly useful in themanufacture of turanalyses: 'bine blading for jet aircraft. These alloysare capable Percent of maintaining their strength and their creep,oxidation, Carbon 0.10-0.20 and thermal fatigue resistance at hightemperatures while Chromium 5-7 still evidencing a reasonable amount ofductility. Molybdenum 1-3 Titanium 0.75-1.50 DESCRIPTION OF THE PRIORART Alummum Cobalt 2-8 The art of nickel base superalloys for jet engineblades Tungsten 5-7 has been developed quite substantially in recentyears. Rhen um 0-1 Typical among the US. patents in this field are thefolloW- Hafnlum 0.3-2.5 ing: 2,570,193; 2,945,758; 2,951,757; 2,974,036;2,977,- Zirconium 0.02-0.30 222; 3,061,426; 3,164,465; 3,166,412. 5 Born 0.010.1 One of the most recent alloys of this type containing Tantalum7-9 substantial amounts of refractory metals is described in Columbium0-1 Freche et al. US. Pat. 3,276,866, issued Oct. 4, 1966. Vanadlum 0-1Commercially available nickel base superalloys are Nickel (1)represented in the following table: 1 Essentially the balance.

TABLE 1.NOMINAL COMPOSITIONS OF CONTEMPORARY NICKEL-BASE SUPERALLOYSCast or Alloy wrought C Cr Mo Ti A1 00 W Zr B Ta Cb V Fe Nimonie W 0.0420.0 InconelX W 0. 04 15.0 Waspaloy W 0.08 19.5 0. 09 10.0 0.08 15.00.12 12.5 0.13 10.0 0.15 9.0 0.125 6.0 0.125 6.0

3,526,499 Patented Sept. 1, 1970 While the art is thus quite highlydeveloped, the stress rupture properties of these alloys can stand asubstantial amount of improvement. To our knowledge, the stress rupturelife of these alloys at an applied stress of 15,000 psi. and at atemperature of 2,000 F. does not exceed 3 DESCRIPTION OF THE PREFERREDEMBODIMENT The alloys of the present invention use substantial amountsof solid solution strengtheners such as tantalum, tungsten, andmolybdenum in proper balance to achieve strength properties withoutdepreciating the oxidation resistance of the alloy. The addition ofhafnium has been found to be particularly effective in securing theproperties desired. The addition of rhenium is optional but may be usedto improve corrosive properties of the alloy in some instances.

In order to illustrate more completely the substantial improvements inphysical properties which are achieved by the alloys of the presentinvention, we are listing below typical stress rupture properties ofexisting alloys under various conditions:

TABLE 2.STRESS RUPTURE PROPERTIES OF CONTEMPORARY ALLOYS (A) 1,800 F.tests Hours of life for given stress, psi.

(B) 1,900" F. tests Hours of life for given stress Wrought niekel-basealloys, Udimet Cast nickel-base alloys:

Ineo 713 0 After considerable experimentation, we determined that thethree best alloy compositions coming within the broader analyses recitedpreviously were the following, wh ch we called alloys IV-Y, VI-A andVI-D:

TABLE 3 Alloy IV-Y: Percent Carbon 0.15 Chromium 6.0 Molybdenum 2.0Titanium 1.0 Aluminum 5.4 Cobalt 5.0 Tungsten 5.5 Rhenium 1.0 Hafnium2.0 Zirconium 0.03

Boron 0.02 Tantalum 8.0

Columbium 1.0 Nickel Balance Alloy VI-A:

Carbon 0.13 Chromium 6.1 Molybdenum 2.0 Titanium 1.0 Aluminum 5.4 Cobalt7.5 Tungsten 5.8 Rhenium 0.5 Hafnium 0.4 Zirconium 0.13 Boron 0.02

Tantalum 9.0 Columbium 0.5

Nickel Balance 4 Alloy VI-D:

Carbon 0.15 Chromium 5.4 Molybdenum 2.0 Titanium 1.0 Aluminum 5.4 Cobalt5.0 Tungsten 6.0 Hafnium 1.75 Zirconium 0.08 Boron 0.02 Tantalum 8.5Columbium 0.5 Vanadium 0.5 Nickel Balance The average stress rupturelife of these three alloys, at 2,000 F. and at an applied stress of15,000 pounds per square inch was 41.3 hours for alloy IV-Y, 62.9 hoursfor alloy VI-A, and 67.3 hours for alloy VI-D.

The physical testing of the samples was carried out in the followingway. The stress rupture testing was performed in air and in commerciallypure argon atmosphere. In the argon tests, the chambers were flushedwith argon before heating and then the atmosphere was maintained afterthe test until the specimen was cooled to less than 1,000 F.

Tensile tests were performed on the specimens as cast and after heattreatment consisting of a 300 hour age at 1,875 F. in an argonatmosphere.

Charpy impact testing was performed on a standard impact tester inaccordance with ASTM standards. The pendulum velocity was 17 feet persecond. The test specimens were unnotched with dimensions of 2.165inches by 0.394 inch by 0.394 inch, and were machined from the as castmaterial.

Thermal fatigue testing was performed in the following manner. Thespecimens were heated with an oxyacetylene fiame, the specimens beingprecision cast wedges 2 inches long, inch at the large end and inch atthe pointed end, and inch wide. Some specimens were run at a testtemperature of 2,100 F. and others at 1,875 F. Temperature measurementswere made with an optical pyrometer. A reading was made after the firstten cycles, at 20 cycle intervals up to 50 cycles, and at 50 cycleintervals thereafter to the completion of the examination interval. Thecycle intervals for crack examination varied for the two testtemperatures. At 2,100" F. the specimens were examined at 30 cycleintervals up to 150 cycles, at 50 cycle intervals up to 400 cycles, atcycle intervals up to 1,500 cycles, at 200 cycle intervals up to 3,100cycles, and at 500 cycle intervals thereafter to failure. The number ofcycles to first crack detection were recorded. At 1,875 F., thespecimens were examined at 50 cycle intervals up to 200 cycles, at 100cycle intervals up to 1,000 cycles, at 200 cycle intervals up to 2,400cycles, and 400 cycle intervals thereafter, to a maximum of 4,000cycles.

Two methods were employed to evaluate the corrosion resistance of thealloys, consisting of oxidation tests and hot corrosion tests. Foroxidation testing, the specimens utilized were 0.5 inch diametercylinders, /2 inch long. The specimens were placed in high purityalumina crucibles and weighed before heating. The specimens in thecrucibles were then heated in air at one of the test temperatures andtimes. A new specimen was used for each test condition. Upon removalfrom the furnace, the crucibles were covered to prevent loss of scaledue to flaking during cooling. After cooling, the crucible and contentswere then weighed to determine the change in weight due to oxidation.

Hot corrosion testing was done by means of a gravimetric method usingthe same size specimen as the oxidation tests. The specimens wereweighed and then partially covered with a 1% sodium chloride, 99% sodium94,000 p.s.i.

Life, E1on., hrs. percent the specimens were reweighed and the loss ofweight used as a measure of the sulfidation attack.

The following tables illustrate representative values obtained whentesting the three preferred alloys of the present invention.

85,000 p.s.i. 00,000 p.s.i.

' Life, Elon., L1fe,- E10n., "hrs. percent ILA. hrs. percent TABLE4.STRESS RUPTURE FOR CAST ALLOYS IN AIR AT 1,400 F.

sulfate mixture in silica crucibles. The crucibles with the specimensand salt mixture were heated in air for 1 hour at a temperature of1,800? F. The scale produced during the corrosion of the specimens wasremoved by cathodical- 1y descaling in molten sodium hydroxide. Afterdescaling,

Alloy 67717901 1 3 2 3L1JL3 35,000 p.s.i.

Life, Elon., hrs. percent 25,000 p.s.i.

Life, Elon.,- hrs: percent TABLE 5.STRESS RUPTURE RESULTS FOR CASTALLOYS IN AIR AT 1,875 F.

main 4 31197 4 25,000 p.s.i.

Life, E1on., hrs. percent 20,000 p.s.i.

Life, Elon., hrs. percent 15,000 p.s.i. Life Elon., .hrs. percent RA.

TABLE 6.-.STRES S RO'PTURE RESULTS FOR CAST ALLOYS IN AIR AT 1,950 F.

753553481 ZHMZA GHMA LKW saaaasa & 3 4352M2 085 21112HMU VID-- R.A.,percent AT 15,000 P.S.I. LOAD Elongation, R.A., Elongation, Life, hrs.percent percent Life, hrs. percent;

TABLE 7.STRESS RUPTURE RESULTS FOR CAST ALLOYS IN ARGON "AHOY IVY036691300 lamuolemd omlm VI-A-..--

VI-D..-...

TABLE 8.TENSILE RESULTS FOR CAST ALLOYS Room temperature 1,200 E. v

Ultimate 0.2% ofiset Elongation, R.A., Ultimate 0.2% ofiset Elongation,RA Alloy (10 p.s.i.) yield (10 p.s.i.) percent percent (10 p.s.i.) yield(10 p.s.i.) percent percent Ultimate 0.2% ofisct Elongation, R.A.,Ultimate 0.2% ofiset Elongation, R.A., Alloy p.s.i.) yield (10 p.s.i.)percent percent (10 p.s.i.) yield (10 p.s.i.) percent percent Ultimate0.2% offset Elongation, R.A., Ultimate 0.2% oiiset ":Elongation, R.A.,Alloy (10 p.s.i.) yield (10 p.s.i.) percent percent (10 p.s.i.) yield(10 p.s.i.) percent percent 69. 8 61. 0 6. 5 6. 6 58. 2 52. 0 6. 3 8. 171. 1 61. 8 5. 9 5. 9 58.0 51. 9 5. 2 6. 2 73. 0 62. 1 4. 4 5. 5 57. 150. 0 6. 0 5. 9 73. 0 63.2 3. 9 4. 7 57. 4 50. 4 3. 8 2. 7 VI-D 73. 665. 5 3. 3 9. 6 60. 0 54. 8 2. 1 2. 0 74. 1 66. 6 2. 2 5. 9 61. 2 56. 12. 3 2. 4

1 Broke in shoulder.

TABLE 9.THERMAL FATIGUE RESULTS FOR CAST ALLOYS First cracking 'lgestAlloy observed Failure temp.,

IV-Y, 1 4, 100 5, 100 2, 100

713C vir in Incol inf" 1, 000 1, 400 2, 100 2 1, 150 1, 600 2, 100

N 100 VT in): I 1- S i 450 1,600 2,100 2 150 1,600 2,100

100 rt IN Li f fu 450 1, 050 2, 100 2 300 300 2, 100

TABLE 10.OXIDATION RESULTS FOR CAST ALLOYS Hot corrosion results foreast alloys Alloygl Y Weight loss (grgnsigg VI A :IZIIIIIIII: 0.150;0.271 VI-D 1.633; 1.968

In addition to the control of the molybdenum, tungsten and tantalumcontents as previously specified, the nickel, aluminum, and titaniumcontents, for best results, should also be controlled. In thisconnection, we prefer to use H the relationship between these metalswhich is specified in U.S. Pat. No. 3,254,994 owned by the assignee ofthe present invention. As, described "in. that patent, it is desirableto produce an intermetallic compound between the three metals, whereinthe compound has the formula Ni A1 Ti where x plus y=1,-but y is notmore than 0.6. This intermetallic compound is a face centered cubicstructure which constitutes the gamma prirne phase of thenickel-aluminum .phase diagram.

4 From our studiesywe have 'concluded'that the preferred alloys of thepresent invention represent a substantial improvement in stress rupturelife over present-day alloys. The alloy identified as VI-A has the besthigh temperature properties of the three. Its stress rupture life is thehighest and represents approximately a 50 F. increase in temperatureover the lives of present-day high strength nickel base alloys. Itstensile strength and impact properties are comparable with suchalloys.Its ductility appears to be adequate and it does not appear to suffer asevere reduction in tensile ductility in the 1,400 F. to 1,600? F.temperature range. In addition, alloy VI-A has a good thermalfatigue'and corrosive resistance for a high strength alloy and does notappear to suffer from microstructural instability, that is, formation ofsigma, Laves, or mu phase formation.

We claim as ourinvention:

1. A nickel-base alloy having improved stress rupture properties andconsisting essentiallyofthe following in- Essentially..thebalancee thesum of the molybdenum, tungsten, and tantalum contents being in therange from 15 to 20%, the tungsten being present in an amount greaterthan the molybdenum but less than the amount of tantalum, the stressrupture life of the alloy at an applied stress of 15,000 p.s.i. at atemperature of 2,000 F. being at least 20 hours.

2. A nickel-base alloy having improved stress rupture properties andconsisting essentially of the following ingredients:

1 Essentially the balance.

the sum of the molybdenum, tungsten, and tantalum contents being in therange from 15 to 20%, the tungsten being present in an amount greaterthan the molybdenum but less than the amount of tantalum, the stressrupture lift of the alloy at an applied stress of 15,000 p.s.i. at atemperature of 2,000 F. being at least 20 hours.

3. A nickel-base alloy having improved stress rupture properties andconsisting essentially of the following ingredients:

Percent Carbon 0.13-0.15 Chromium 5.4-6.1 Molybdenum 1-3 Titanium0.75-1.50 Aluminum 5.0-6.0 Cobalt 5 .0-7.5 Tungsten 5.5-6.0 Rhenium -1.0Hafnium 0.43-2.0 Zirconium 0.03-0. 13 Boron 0.01-0.1 Tantalum 8 .0-90Vanadium 0-0.5 Nickel (1) 1 Essentially the balance.

the sum of the molybdenum, tungsten, and tantalum contents being in therange from 15 to 20% the stress rupture life of the alloy at an appliedstress of 15,000 p.s.i. at a temperature of 2,000 F. being at least 20hours.

4. The alloy of claim 1 in which there is sufiicient nickel present toprovide the compound Ni Al Ti where x plus y: 1, but y is not greaterthan 0.6-.

5. A nickel-base alloy having improved stress rupture properties andconsisting essentially of the following ingredients:

Percent Carbon 0.15 Chromium 6.0 Molybdenum Titanium Aluminum 5.4 Cobalt5 Tungsten 5 Rhenium 1.0

Percent Hafnium 2.0 Zirconium 0.03

Boron 0.02

Tantalum 8.0

Columbium 1.0

Nickel (1) 1 Essentially the balance.

said alloy having a stress rupture life at an applied stress of 15,000p.s.i. at a temperature of 2,000 F. of at least 20 hours.

6. A nickel-base alloy having improved stress rupture properties andconsisting essentially of the following ingredients:

Percent Carbon 0.13 Chromium 6.1 Molybdenum 2.0 Titanium 1.0 Aluminum5.4 Cobalt 7.5 Tungsten 5.8 Rhenium 0.5

Hafnium 0.43

Zirconium 0.13

Boron 0.02 Tantalum 9.0 Columbium 0.5 Nickel (1) 1 Essentially thebalance.

said alloy having a stress rupture life of at least 20 hours at anapplied stress of 15,000 p.s.i. and at a temperature of 2,000 F.

7. A nickel-base alloy having improved stress rupture properties andconsisting essentially of the following ingredients:

Percent Carbon 0.15 Chromium 5.4 Molybdenum 2.0 Titanium 1.0 Aluminum5.4 Cobalt 5.0

Tungsten 6.0 Hafnium 1.75 Zirconium 0.08 Boron 0.02 Tantalum 8.5Columbium 0.5 Vanadium 0.5 Nickel (1) 1 Essentially the balance.

said alloy having a stress rupture life of at least 20 hours at anapplied stress of 15,000 p.s.i. and at a temperature of 2,000 F.

8. A turbine engine blade composed of the alloy of claim 1.

9. A turbine engine blade composed of the alloy of claim 2.

10. A turbine engine blade composed of the alloy of claim 3.

References Cited UNITED STATES PATENTS 3,005,705 10/1961 Cochardt 1713,164,465 1/ 1965 Thielemann 75171 3,310,399 3/1967 Baldwin 75-171RICHARD O. DEAN, Primary Examiner UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No. 3,526 499 Dated September 1, 1970Inventor(s) Richard]. Quigg and Henry E. Collins It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 7, line 18, (second table of Table 8, in the third column) "104.4" should read --140. 4--.

Column 8, line 35,

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